复合绝缘子伞裙老化评估的核磁共振分析方法及传感器研究

发布时间：2018-05-02 09:17

本文选题：复合绝缘子 + 老化评估　；参考：《重庆大学》2014年硕士论文

【摘要】：复合绝缘子以其重量轻，机械强度高，耐污性能好等优良性能，在高压输电线路中得到了广泛的应用。然而，随着复合绝缘子使用量的剧增和挂网运行时间的增长，复合绝缘子的老化问题越来越受到电力运行部门的关注。开展复合绝缘子老化状态评估及检测方法研究，对于及时发现缺陷，避免由此带来的线路事故，保障电力系统的安全稳定运行意义重大。现有的检测方法或不够准确，或不能无损测量。本文提出采用低场核磁共振技术来实现对复合绝缘子伞裙老化状态进行无损检测，并以此为目标开展了基于低场核磁共振原理的复合绝缘子伞裙老化特性的初步研究。本文的主要工作内容如下： ①提出基于低场核磁共振的复合绝缘子伞裙老化检测方法，并对低场核磁共振的检测原理进行分析研究。 ②根据复合绝缘子伞裙的结构特点，设计并制作了夹钳结构的便携式核磁共振传感器。该传感器由夹钳式结构、磁体结构、射频线圈及调谐匹配电路四部分组成，连接到核磁共振谱仪上，可实现对复合绝缘子伞裙的无损检测。 ③研究了核磁共振回波信号的拉普拉斯逆变换分析方法，在对回波信号反演分析研究的基础上制作了核磁共振回波分析软件，能够实现对低场核磁共振弛豫信号进行单指数、双指数函数拟合和拉普拉斯逆变换处理。 ④对在同一输电线路上挂网运行不同年限的复合绝缘子进行便携式核磁共振测量实验，，采用核磁共振回波分析软件进行处理，选取由拉普拉斯逆变换得到的核磁共振特征量横向弛豫时间T2long mean表征复合绝缘子的老化程度。实验结果表明，随着运行时间的增加，复合绝缘子伞裙老化程度加重，对应的横向弛豫时间呈减小的趋势。因此，用便携式低场核磁共振传感器测量得到的T2long mean横向弛豫时间来反映复合绝缘子的老化程度是可行的。本文的研究工作有助于建立基于低场核磁共振的复合绝缘子老化特性评估的新方法，对于开展复合绝缘子伞裙老化特性及老化机理的研究，科学评估复合绝缘子的使用寿命具有重大的现实意义。
[Abstract]:Composite insulators are widely used in high voltage transmission lines because of their light weight, high mechanical strength and good pollution resistance. However, with the rapid increase in the use of composite insulators and the increase in the operation time of the grid, the aging of composite insulators has attracted more and more attention from power operation departments. It is of great significance to study the aging state assessment and detection method of composite insulators for detecting defects in time, avoiding line accidents and ensuring the safe and stable operation of power system. Existing testing methods are either not accurate or nondestructive. In this paper, a low field nuclear magnetic resonance (LFS) technique is proposed to detect the aging state of composite insulator skirt, and the aging characteristics of composite insulator skirt based on the principle of low field nuclear magnetic resonance (LFNMR) are studied. The main work of this paper is as follows: The main contents are as follows: 1. The aging detection method of composite insulator skirt based on low field nuclear magnetic resonance (LFNMR) is proposed, and the principle of low field nuclear magnetic resonance (LFS) detection is analyzed. According to the structural characteristics of composite insulator umbrella skirt, a portable nuclear magnetic resonance sensor with clamp structure is designed and fabricated. The sensor is composed of clamp structure, magnet structure, RF coil and tuning matching circuit. The sensor is connected to the NMR spectrometer and can be used for nondestructive testing of composite insulator umbrella skirt. 3. The inverse Laplace transform analysis method of nuclear magnetic resonance echo signal is studied. Based on the inverse analysis of the echo signal, a nuclear magnetic resonance echo analysis software is made, which can realize the single exponent of the low field nuclear magnetic resonance relaxation signal. Double exponential function fitting and Laplace inverse transform processing. (4) the portable nuclear magnetic resonance measurement experiment is carried out for composite insulators with different years of operation on the same transmission line, and the nuclear magnetic resonance echo analysis software is used to process them. The transverse relaxation time (T2long mean) obtained from the inverse Laplace transform is selected to characterize the aging degree of composite insulators. The experimental results show that the aging degree of composite insulator umbrella skirt increases with the increase of running time and the corresponding transverse relaxation time decreases. Therefore, it is feasible to use the T2long mean transverse relaxation time measured by a portable low-field NMR sensor to reflect the aging degree of composite insulators. The research work in this paper is helpful to establish a new method to evaluate the aging characteristics of composite insulators based on low field NMR, and to study the aging characteristics and aging mechanism of composite insulator skirt. It is of great practical significance to evaluate the service life of composite insulator scientifically.
【学位授予单位】：重庆大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TM216

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